I've seen this drama around before, but always passed on watching it. Finally, I decided to just give it a go and found myself really enjoying this drama.

The story was entertaining, although some parts felt a bit draggy, I was still invested in the story. The episodes leave you on a cliffhanger, so when you say "just one more episode", it's never just one more episode. You have to start the next one to find out what happens.
The OST was fine. Nothing great, but it worked.
The characters/actors are what made me enjoy this so much. I think they chose the perfect actors to play these characters. When it comes to Song Seung Hoon, his dramas are usually hit or miss for me. This one was definitely a hit. I thorougly enjoyed his portrayal as Ha Ri. Krystal was also a stand out for me. I enjoyed her portrayal as Ah Ryung. In fact all four of them fit together really well. The friendship between them was there and I really enjoyed the dynamics between the group. You definitely grow attached to these characters.
This is definitely a rewatchable show! Overally, an enjoyable show that will keep you invested throughout!